You may think you have everything you need to start a successful business or build a successful career: Startup money, industry contacts, a great product, a clear vision of where you want to go, and the drive and stamina to get there.

There's one other element you need to truly achieve success, and it's one we rarely talk about in business publications and websites: Community. Surround yourself with a community of like-minded people who are ready to help and support you, and whom you can help and support in return and you'll reap benefits you couldn't even imagine.

I saw the power of community in action recently at a Women's Leadership Retreat presented by executive coach and bestselling author Wendy Capland. For the past couple of years, I've been working with Capland as my coach and writing about what I've learned. Being on opposite coasts, we'd always met by phone so the retreat gave me the chance to finally meet Wendy in person, and also what she calls her "board of girlfriends," some of whom have been attending this annual event for decades.

The content of the retreat itself was great, but its biggest power was in this community of managerial and entrepreneurial women, all committed to our careers and making a better future. There was the strong sense that the women in that room would do whatever they could to help each other, including delivering support, opportunities, and hard-to-hear truths (which happened to me once or twice in the course of the event). I took part in this exchange of help and opportunity as well. When one woman in the group stood and told everyone else that she was feeling isolated and needed more connections, many of us volunteered to get on the phone with her and some of us wound up doing business with her as well. Perhaps my favorite part of the event was a table in the corner covered with little squares of paper and envelopes we were invited to use to send each other love notes. I wrote a bunch of those and got a bunch myself and opening my envelope to see who'd written me what was something like opening presents on Christmas morning.

What can community do for you? Here's a partial list:

1. Encouragement and shared knowledge.

The life of an entrepreneur is famously lonely, and even managers in large organizations can feel isolated, depending on the nature of their jobs and workplaces. Being part of a group of people who share your concerns and goals can go a long way toward lessening that isolation. Talking to people who are facing the same challenges you are, and are willing to share encouragement, can cut seemingly daunting obstacles down to size.

Just as important, having a community means shared knowledge. A few years ago, I got into a business deal that started to go south almost immediately. I felt taken advantage of by the customer but I had signed a long-term contract which meant I couldn't just walk away. I asked for advice from some of my colleagues in the American Society of Journalists and Authors who confirmed my sense that the customer was being unreasonable and recommended a lawyer to call. I did, and suddenly my problem was solved.

2. Networking.

The business world runs on personal contacts, and the best way to make those contacts is through a community in your industry or profession. I can't even count how much business I've gotten through the years from contacts like these. Among other advantages, that's saved me eons of time compared to making cold calls or sending pitches to people with no personal connection.

3. Examples of success.

Few things are as powerful to help you succeed as seeing someone you know accomplish what you want to. Suddenly, whatever it is goes from pipe dream to everyday reality. Consciously or unconsciously you'll start thinking that if he or she can do it, then so can you. I experienced this myself: I'd been noodling around with the manuscript for a book for more than a decade when someone I knew wrote a whole book from start to finish in six months. That made me realize that I'd been wasting a lot of time and propelled me to get my draft done as well.

4. Help when you're in trouble.

We all run into trouble some time or other and when it happens, being part of a community makes all the difference. I found that out myself a few months ago when my husband and I bought a house and had to move out of our rental. Our lease was up so the clock was ticking. Unfortunately, in addition to our usual work schedules, we were spending much of our time in the hospital with a dear friend who was gravely ill. On top of that, I developed a raging infection in my mouth that hurt so much it was difficult to think straight.

I needed oral surgery ASAP, but I'd been warned it would put me out of commission for a couple of days and the deadline for moving was upon us. It would be a stretch for us to get packed in time. With the surgery there was no chance.

"I don't know what to do," I told my husband Bill.

"We have friends," he told me. And he put out word to the community of local musicians that had become our second family here that we were in trouble. Over the next few days, many of them arrived at our house and packed and packed until all the packing was done. Some brought trucks and helped us move our boxes and small furniture, leaving only the biggest items for the professional movers we hired. As I languished with an ice pack pressed to my face, the move was accomplished without me. It was a profound lesson in how having a community behind you can make all the difference when things go wrong.

5. Extra years of life.

It may sound unlikely but it's true. National Geographic writer Dan Buettner spent years traveling the globe and visiting communities where surprisingly large numbers of people live to be over 100, usually in excellent health. He found that these widely diverse groups had a few things in common, and one of them was that the long-lived people there were all part of tight-knit communities. One group, the Okinawans, have a tradition called Moai in which people form social support groups for the common interest in which they help each other through hard times and share their fortunes in good times. Buettner found being part of a community can actually help you live longer.

Communities are everywhere.

As professionals, we tend to think in terms of the communities formed in our industries, workplaces, and professional groups. But there are all kinds of communities in lots of places, and they can all help you in unexpected ways. One friend of mine has landed some great business deals from the high-powered fellow parents at her daughter's play group. Communities can form around your neighborhood, your gym or yoga studio, your political preferences, or by connecting through a Meetup or social networking group. So look for your community and you'll find it. And once you do, both your career and your life will never be the same.